A technology is known, which transmits an impact load, entered from a side direction of a vehicle at a time of collision, to a vehicle body floor via a seat. (See, for example, Patent Document 1).
According to a vehicle seat disclosed in Patent Document 1, a reinforcing member is installed on a back side of an upper frame of a seatback frame. The reinforcing member is elongated beyond a seatback width towards an outer side in the vehicle width direction. As a result, an impact load inputted from a side part of a vehicle body is transmitted to a seatback frame through the reinforcing material. Further, according to this vehicle seat, an airbag unit is supported by an area of the reinforcing material extending towards an outer side in the vehicle width direction. As a result, a reactive force, occurring at the time when an airbag deploys, is received by the reinforcing material.